Re: [Orgmode] Feature request: IDs on anything

[Samuel Wales]

I wrote this a long time ago in response to Carsten's reply
to Eric in the first link below.

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  1) http://thread.gmane.org/gmane.emacs.orgmode/11896
     extensible syntax with an application in id markers
     (which themselves have an application in many things,
     including graph theoretic constructs such as planning
     tours)
  2) http://thread.gmane.org/gmane.emacs.orgmode/10204/focus=10240
     extensible syntax and parsing risk

===

Yes, ID markers are merely link /targets/.  :)

The :link option (which the user can decide to put in or
leave out) turns them into link /sources/ (clickable and
RET-able elements) also.  This allows bidirectional links by
having two ID markers link to each other.[fn:46] A future
post will describe an application.

Perhaps you are thinking of new link features beyond :link?
These are possible, but they are not part of my proposal.

For example, you know how in a browser the links change
color if you have visited them in the last n days?  It
usually seems to be blue links turning red.  That helps you
keep track of things.

If it is ever desired, we can implement this in org.  We add
an option, :last-followed, which contains a timestamp for
the last time you followed the link.  When that timestamp is
within the last n days, org changes the color of the ID
marker's label to red.  (Or it can make it more red the
longer it's been.  Or show how many days it's been.)

I'm *not* saying this feature is necessary, of course (it
isn't).  The point is just that the syntax is robust against
the future, including ideas like this.

P.S.

You don't have to use an ID marker if you never want to
point to it.  If you still wanted fancy link features, then
you could implement something like this instead of using ID
markers.

  $[link http://google.com
         :last-followed [2009-02-27 Fri 02:00]
         :label "click here for evil search engine"
         :export-label "click here for nice search engine"]

(I threw in an export label just for fun.)

But I'm only proposing ID markers (and extensible syntax).

[fn:46] :link enables bidirectional links, rings, DAGs,
tours (e.g. for tutorials), multiple planning sequences,
Bayes nets, decision trees that span the outline's ontology
structure, and adventure games.  In graph-theoretic terms,
an ID marker that uses the :link option is an =arc=;
wherever you place it becomes a =node=.  Arcs can be
unidirectional or bidirectional.